Sometimes it's not even obvious for external contributors, but there may be some small overlap with other paid features that are part of their product roadmap.
If a project on Github only has maintainers from the corporate side, you can be certain that they will ultimately drive the product for their own interest solely.
We should always pay close attention to the governance model of projects we depend on or that we wish to contribute to.
The only way to know for sure is to dive into the merged and unmerged PRs and see how they were handled.
To not lose control you need to have people assign copyright which is generally a headache. I've only heard of the FSF doing that .. (not sure why this hasn't been streamlined electronically somehow)
Fair enough, let's see the PRs so we can judge for ourselves.
OSS doesn't mean that you have to accept any PRs that showed up in your repo, nor does it mean that you have to let a competitor steer your project simply because you're building in the open. Without further elaboration, what you're calling "upstream fixes" may have been considered "working as intended" at HashiCorp. As I'm sure you're well aware, every contribution has to be maintained and each increasing contribution comes with an additional burden. Responsible maintainers on large scale OSS projects must be selective about the code they let in.